The Preparation, Characterization And Properties Of Cds Nanowires Research And Its Application In Thin Film Solar Cell Production

PLD (pulsed laser deposition) is usually a simple, efficient deposition method which is suitable for multiple kinds of materials and can obtain good crystallinity in a relatively lower substrate. In the functions of catalyst, temperature of substrate, and laser pulse energy, there can be one-dimension nano-structure efficiently growing on the substrate, not only flat polycrystalline film. In this paper, we study the wide direct band II-VI semiconductor CdS, and deposit a kind of combination of flat films and nano-wires with PLD through adjusting the conditions mentioned above. And then study its morphology, character and growing mode.First, in the vacuum of2×10-3Pa, ablate the high purity Ni target with the frequency doubling Nd:YAG pulsed laser (532nm). The plume will sputter on the opposite Si substrate and form particles of5～20nm distributing on the Si (100). Heat the substrate to a temperature between300and500℃, and ablate the CdS target for40min, so the plume will sputter on the substrate with catalyst. In this process, adjusting the quantity of catalyst, the temperature of substrate and the laser pulsed energy will change the morphology of the film from flat polycrystalline film to a combination of polycrystalline and nano-wires. The morphology can be observed by SEM. When the Ni depositing time is10min, and the temperature is450℃, dense CdS nano-wires growing from the substrate, orienting disorderly with a density of3.7*10cm-2. Exam the background, the polycrystalline can be observed. TEM shows that single nano-wire is needle-like, with sharp tip and wide root, and the middle diameter and length is50nm and800nm respectively. HRTEM and SAED results show that single nano-wire has perfect hexagonal structure, and XRD validates the hexagonal structure and shows that the combination of polycrystalline and nano-wires has more growing directions. PL shows that the CdS has good crystallinity and less defects.The substrate temperature, quantity of catalyst and pulse energy all has effects to the growing of nano-films. If keep the Ni depositing time, pulse frequency&energy unchanged (10min,5Hz,50mJ) and just adjust the temperature, we can find that there will be no nano-wires but only fuzzy blocks until the temperature raised to350℃. When it reaches to450℃, the density of nano-wires reaches to the highest. Then the higher temperature it is, the lower density it will get until there’re no nano-wires at all when it is up to600℃. If keep the temperature at400℃and change the quantity of catalyst, we can found that if without or with low quantity, no nano-wires can grow out. When raise the Ni depositing time to10min, there be a combination of good polycrystalline and single well-growing nano-wires. If raise the quantity of catalyst, the density of nano-wires declines. Keeping the temperature and catalyst unchanged and adjust the pulse energy, we’ll find that if the energy is too high, nano-wires can’t grow out, while if the energy is too low, there’ll be small balls standing on the top of nano-wires which even lead to a second growing of small nano-wires on the top. This adequately proved that the growing of nano-wires follows the VS and VLS mode.Again, in this paper we also discussed the fabrication of polymer solar cell, the composite nano-structure of P3HT:PCBM/CdS, CdTe/CdS and their potential application in thin film solar cell.